Adds a new landing page for developer events, starting with the v21 page. It also includes an ICS file link for calendar invites. Also updated the tests for the docs-pill to support two new attributes so developers can add the event to their calendars.
The ExampleViewer component was extracting only innerHTML from code
blocks in multifile examples, which lost the shell class applied by
the formatCode function. This caused the $ prompt to not appear for
shell commands in multifile blocks even when language="shell" was set.
Modified the Snippet interface to track shell language state and
updated getCodeSnippetsFromMultifileWrapper and getStandaloneCodeSnippet
methods to preserve the shell class. Updated example-viewer template
to conditionally apply the shell class to the code wrapper element.
Fixes inconsistency between standalone and multifile shell code blocks.
